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Ovulation

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involves rupture of one or more mature ovarian follicles and the shedding of some of its contests from the surface of the ovary

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Corpus Luteum

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The remainder of a follicle after its shedding of contents under hormone influence

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Progesterone and estrogens

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The corpus luteum is an important endocrine structure secrete these, which produce uterine changes facilitating the implantation and the maintenance of the conceptus

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luteinising hormone

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Ovulation is controlled by this. mechanism of action is thought to be increased pressure within the follicle

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adenohypophysis

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produces L.H. (glandular pituitary)

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Germ cell, 1st polar body, zona pellucida, corona radiate

answer

structures shed from the ovary (4)

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Germ cell

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in the form of a secondary oocyte, arrested in metaphase

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1st polar body

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formed in the 1st meiotic division just prior to ovulation

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zona pellucida

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membranous envelope of mucopolysaccharide surrounding germ cell and 1st polar body

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corona radiate

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a surrounding layer of follicular epithelial cells. in the horse and dog the germ cell ovulated is unusually a primary oocyte whose dicision has yet to be accomplished.

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oocyte nucleus with nucleolus, oocyte, vitelline (oocyte) membrane, perivitelline space, 1st polar body, zona pellucida, corona radiata

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innermost to outermost structures (7)

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peritoneal cavity

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structures are shed from the surface of the ovary to this

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Oviduct, fallopian tube, uterine tube

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From the peritoneal cavity, the ovum pass into this structure

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infundibulum

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the transport of the ovum is assisted by the the action of the cilia of this structure

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peritoneal fluid

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second factor to ovum transport

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mascular contractions of the tube

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once the germ cell is in the tube, passage is assisted by this and the action of its cilia.

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(1)Infundibulum, (2)ampulla, (3)isthmus

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makes up oviduct

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spermatozoa

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at insemination, millions of these male germ cells are deposited in the vagina.

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capacitation

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Although stucutrally full mature, spermatazoa have yet to undergo this (to acquire thier ability to fertilize the female germ cell)

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Muscular contraction of female tract and motility of sperm.

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Fast transport time is achieved by 2 things. the cilia of the uterine tube do not assist.

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1-2 days. 6-7 in dogs/horses, 32 days in fowl, 70 in turkey

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Sperm Viability

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ampulla region of uterine tube

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site of fertilization

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12-24 hrs

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time after ovulation that fertilization occurs. important factor along with sperm viability.

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Corona radiata, zona pellucida, cell membran of oocyte

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3 barries which the spermatozoon must potentially overcome to fertilize.

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corona radiata

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usually already fragmenting by the time of fertilization (gone in the ox)

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acrosome

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zona pelludcida isn't a barrier because it is thought to be overcome by the action of exymes produced in this part of the sperm.

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tail of sperm is shed and cell membranes of male and female germ cells unite.

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what happens to the cell membrane of the oocyte during fertilization

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2nd meiotic division

answer

happens immediately after penetration which produces the ovum

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2nd polar body

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also produced during second meiotic division

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block to polysperray

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causes no further sperms to penetrate

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cortical reaction

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cortical granules in the oocyte cytoplasm align at the periphery of the oocyte, adjacent to the plasma membrane of the oocyte

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female and male proneclei

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haploid joining of male and female nuclei

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zygote (diploid) and polar bodies

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lie in the zona pellucida after fertilization

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stages of fertilization

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1) penetraction of the corona radiate
2) bringing to an penetration of the zona pellucid by the spermatozoon
3)contact of the spermatozoon withe the vitelline membrane
4) zona reaction
5) entry of the spermatozoon into the ovum
6) formation and fusion of the pronuclei and zygote.

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2- cell zygote (2 cell stage)

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prior to fusion the female and male pronuclei dupilcate their DNA content and immediately on fursion their chromosomes split in the course of a normal mitotic division, resulting in formation of a

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polyspermy

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more than 1 sperm penetration, 3 results in triploid embryo. common in pig and usually die in early stage.

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cleavage or segmentation

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from the 2-cell stage progressive cell division occurs without overall increase in the size. all cells are still within the zona pellucida. Results in progressively smaller daughter cells.

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blastomeres

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smaller daughter cells during cleavage

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morula

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when the conceptus is converted into solid ball of blastomeres. little mulberry

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deutoplasm

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Nutrition during morula formation is from yolk droplets contained within the cytoplasm of the cells known as this

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lumen of uterine tube

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up to the morula stage, the conceptus lies here freely.

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Zona pellucida

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After the morula, this disappears and now the coceptus is free to enlarge and rapidly grows to fill the uterine lumen

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blastocyst

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Intercellular fluid-filled spaces appear, then caolesce into a cavity. at this point the conceptus is termed this

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blastocoele

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the enclosed cavity of the blastocyst is called the

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embryoblast

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inner cell mass of the blastocyst

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trophoblast

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outer cell mass

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embryo proper

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the embryoblast gives rise to this

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extra-embryonic membrane

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trohoblast forms to give this. associate with nutrition of the embryo.

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endometrial glands

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nutrition of the blastocyst is selective diffusion through the trophoblast derived from secretions of

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end of week 1, end of week 2 in dogs.

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blastocyst stage is reached towards the end of this week.

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end of week 1, end of week 2 in dogs.

answer

blastocyst stage is reached towards the end of this week.

question

central implanation

answer

implanataion in the uterus. Domestic species the embryo remains loacted in the uterine lumen termed

question

interstital implantation

answer

in man and guinea pig the conceptus migrates through the uterine epithelium into the substance of the endometrium

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progesterone

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in the process of implantation, structural changes in the endometrium and in the conceptus occur under the action of this substance from the corpus luteum

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elongation of the blastocyst

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particularly in the pig, this occurs greatly increasing teh surface area of contact between the trophoblast and uterine epithelium. simple adhesions develop followed by the formation of junctional complexes

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pig-12
dog-18
sheep-10, completed 4-5 wks
horse- 2 months, complete 14 weeks.

answer

implantation times

question

polytocous

answer

bearing many yong

question

dizygous

answer

two seperate ova are fertilized. pigs and carnivores.

question

monozygous

answer

one ovum is fertilized but divides at blastocyst stage. sometimes in man and cow

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Ectopic

answer

fertilized ovum in peritoneal cavity and implanted into peritoneal surface. Death usually follows. sometimes in uterine tube of man (tubal pregnancy).

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zp avoids direct contact between trophoblast and maternal epithelium and delays expansion while it is in the tube.

answer

reason why tube preg. normally doesn't occur

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freemartin

answer

idzygous twinning, development of common circulation by placcental anastomosis usually occurs. if opposite sex, the female is known as (intersex)

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gastrulation

answer

process whereby the blastula which is a single-layerd structure to a trilaminar structure

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ectoderm
mesoderm
endoderm

answer

classic germ layers

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embryonic endoderm

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inner cell mass cells/embryoblast give rise to a second layer of smaller, darker cells by the process of delamination

question

epiblast

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the covering of the trophoblast cells over the embryoblast disappears. exposed cells of the embryoblast proliferate to form the

question

bilaminar germ disc/embryonic disk

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epiblast produces this, which is still continuous with the trohpoblast

question

trophectoderm or extraembryonic ectoderm

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endoderm now spreads outwards from the germ disc to line the internal aspect of the trophoblast which is named

question

hypoblast

answer

the endoderm so formed is called this. and it encases the yold sac or primitive gut

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bilaminar omphalopleure

answer

2 layered wall is called

question

primitive streak

answer

rapid growth of the embryonic disk occurs in an uneven manner, conerting the ovoid disk into a pear shaped structure. a whiteish line appears on the the embryonic ectodermal layer termed

question

mesoderm

answer

from the primitive streak cells invaginate between the endo and ecto of the germ disc. forms the 3rd germ layer called the

question

intraembryonic mesoderm.

answer

mesoderm spreads throught most of the embryonic disk as the ___ thus converting it into a trilaminar germ disk.

question

extraembryonic mesoderm

answer

the mesoderm spreads beyond the limits of the embryonic disk proper and gives rise to the

question

trilaminar ophalopleure

answer

the extraem. meso spreads between the extraem. ect and the extaem end.o, thus forming the

question

Node of Hensen or primitive node

answer

the cranial extremity of the primitve streak presents a rounded expansion termed the

question

notochord

answer

from the primitive node, cells invaginate and migrate forming a rod of MESODERMAL cells called the

question

buccopharyngeal membrane

answer

the notochord extends as far cranial as the____ (prochordal plate) and is the first indication of a future mouth

question

parazial
intermediate
lateral

answer

3 layers of intraembryonic mesoderm

question

buccopharyngeal and cloacal membranes

answer

2 circular zones of the disc that are not invaded by mesoderm remain bilaminar and are termed

question

somites

answer

Beginning cranially, transverse fissures appear in the PARAXIAL region of the mesoderm to produce paired blocks of mesodermal cells which are called

question

vertebral segment; 4-6

answer

usually there is one pair of somites per _____ and ___ in the head.

question

skeletal, muscular, and dermal elements

answer

somites form

question

sclerotome
myotome
dermatome

answer

3 parts of differnetiating elements in somites

question

nephrogenic mesoderm

answer

INTERMEDIATE mesoderm forms precursors for kidney and some parts of the genital system. Referred to as

question

embryonic somatopleure

answer

Forms parts of the body wall except musculature and ribs

question

Splanchnoplure

answer

Forms most of the gastrointestinal tract located in the thorax and abdomen

question

exocoelom, extraembyonic coelom

answer

the EXTRAem. MESODERM starts to split into 2 layers separated by a cavity called the

question

Intraembryonic coelom.

answer

the exocoelom cavity within the mesoderm spreads gradually to involve the lateral plate mesoderm within the embryo, thus froming the

question

somatopleure

answer

the ectoderm/medoderm layer is termed

question

splanchnopleure

answer

the endoderm/mesoderm layer is the

question

peritoneal cavity

answer

the intraembryonic coelom thus formed within the lateral plate mesoderm is the future

question

peritoneal cavity

answer

the intraembryonic coelom thus formed within the lateral plate mesoderm is the future

question

intraembryonic

answer

from the intraembryonic coelom on either side spreads cranial to untie the midline, cranial to the buccopharyngeal membrane. thus the entire _____ Is horseshoe shaped

question

pericardial cavity; pleural cavity

answer

the midline region is the future____; while the narrow intermediate region is the primitive

question

somites; head

answer

the flat structure of the embryogenic part of the gastrula developes into a tubular structure shortly after the ____ appear, initially in the ____ region

question

one tube insdie the other

answer

Basic pattern of the adult vertebrate

question

body wall (ecto and meso)

answer

outer tube

question

digestive tube (meso and endo)

answer

inner tube

question

coelomic cavity

answer

space between the inner and outer tubes (digestive and body wall)

question

notochord (3)

answer

the ____ serves as the inductor of the formation of the head.

question

neural plate (2)

answer

thickening of the ectoderm over the cranial end of the notochord to form the ______ ______ (precursor to the brain)

question

neural tube (1)

answer

neural plate folds and forms the ____ ____ (later differentiates into the major parts of the brain)

question

neural crest cells (4)

answer

appearance of ____________________ on the dorsolateral sides of the nerual tube.

question

- pigmented cells
-glial cells of cns
-chromaffin cells of adrenal medulla
-neurelemocytes (schwann cells)of periphrial nerves
(4)

answer

neural crest cells give rise to

question

head region forms first

answer

Early features of the head #1

question

most advanced part of the body

answer

Early features of the head #2

question

specific modifications of the basic cylindrical pattern are first seen in this region, even before the body was in the more caudal areas.

answer

early features of the head #3

question

cr. end frows up and forward, then folds back (head fold)

answer

formation of the head #1

question

at same time as #1, lateral folding of ectoderm on each side

answer

formation of the head #2

question

cr. end exto encompasses meso

answer

head formation #3

question

2 lat. folds fuse w/ eachother ventrally results in cylindrical outgrowth. rostral end is closed cuz of forward growth

answer

head formation #4

question

cylin. outgrowth is the head

answer

head formation #5

question

foregut

answer

head #5, inner tube is the

question

ectoderm covering head is continuous w/ rest of ecto

answer

head #6 ectoderm

question

head is elongated by continued growth and folding

answer

head #7 elongation

question

incorporates the first several pr of somites to form the musculo-skeletal sructures of the head.

answer

head #8 cadual part of head

question

telen and dien

answer

brain subdivisions of prosencephalon

question

cerebral cortex
basal nuclei
limbic system

answer

derivatives of prosencephalon (telencephalon)

question

lateral ventricles

answer

associated ventricles of prosencephalon
(telencephalon)

question

epithalamus
thalamus
hypothalamus

answer

major derivatives of diencephalon (prosen)

question

third ventricle

answer

associated ventricles of dien (prosen)

question

mesencephalon (mid brain)

answer

Brain subdivision of mesencephalon

question

tectum
corpora quadrigemina
tegmentum
cerebral peduncles

answer

major derivatives of mesencephalon

question

mesencephalic aqueduct

answer

associated vetnricle of mesen

question

rhombencephalon

answer

hind brain

question

metencephalon and myelencephalon

answer

subdivisions of rhomben

question

pons
cerebellum

answer

major derivatives of meten (rhomben)

question

rostral part of 4th ventricle

answer

associated ventricle of meten (rhomben)

question

medulla oblongata

answer

Major derivatives of myelencephalon (rhomben)

question

cd. part of 4th ventricle

answer

associated ventricle of myelencephalon (rhomben)

question

curved cylindrical structure

answer

result of body folding. embryo goes from flat disc to

question

somatopleure

answer

lat. and ventral body walls develop by folding of the

question

gut

answer

the ___ is formed by being nipped off from the yolk sac and trapped within the developing body of the embryo

question

vitello-intestinal duct

answer

the gut communicated with the yold sac at first widely and later narrowly by the ________

question

fluid filled amnion

answer

result of folding: the embryo is completely surrounded by the

question

future umbilical cord.

answer

a group of structures are bunched together at mid-abdominal level. these structures are the

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