Chapter 4 - Reproduction and Development Flashcards
What reproductive hormone is released from the hypothalamus to the anterior pituitary?
gonadotropin releasing hormone (GnRH)
What gonadotropin hormones are released from the anterior pituitary to the gonads?
- luteinizing hormone (LH)
- follicle stimulating hormone (FSH)
What are the male and female gonads?
testes and ovaries
What are the two responses of the gonads to gonadotropins?
- production of steroid hormones
- production of germ cells
What are the germ cells in males and females?
spermatazoa and ova
Define spermatogenesis
production of sperm
What are the spermatogenic cells called that are closest to the basement membrane of the seminiferous tubule and how many chromosomes do they have?
spermatogonia - 46 chromosomes
What is the product of the mitotic division of the first spermatogenic cells and how many chromosomes do they have?
two primary spermatocytes - 46 chromosomes each
What is the product of the first meiotic division of spermatogenic cells and how many chromosomes do they have?
2 secondary spermatocytes - 23 chromosomes each
What is the product of the second meiotic division of spermatogenic cells and how many chromosomes do they have?
two spermatids - 23 chromosomes each
Each primary spermatocytes produces how many spermatids?
4
What is spermatogenic transmortion?
spermatids bud out to form spermatozoa
What structure of the spermatozoa helps them digest the lining of the egg?
acrosome
What is the function of Leydig cells?
They convert cholesterol to testosterone
What does testosterone do in Sertoli cells?
It binds a receptor, converting into dihydrotestosterone, which diffuses into the nucleus and instructs DNA to synthesize RNA.
What does LH do in the testes?
It binds to Leydig cell receptors resulting in a second messenger that increasing the conversion of cholesterol to testosterone.
What does FSH do in the testes?
It binds to Sertoli cell receptors, resulting in a secondary response that converts testosterone to hydrotestosterone.
What feedback mechanism results if testosterone is too high?
It inhibits the hypothalamus’ release of GnRH and anterior pituitary’s release of LH.
What feedback mechanism results when dihydrotestosterone is too high?
It inhibits the anterior pituitary’s release of FSH.
What hormone is responsible for secondary sex characteristics in the male?
testosterone
Where is sperm stored?
in the epididymis and vas deferens
Define oogenesis
production of ova
In oogenesis, what occurs during the 2-3 months of female fetal development?
Oogonia undergo mitotic division to produce primary oocytes.
Define atresia
the degeneration of immature primary oocytes
What happens to primary oocytes during monthly cycles?
There is s surge in LH, causing the first meiotic division that produces a secondary oocyte (23 chromosomes) and first polar body.
What happens to the secondary oocyte after fertilization?
It undergoes the second meiotic division to form an ovum (23 chromosomes +23) and a second polar body.
What happens in the follicular phase?
The primary oocyte develops into the secondary oocyte and an LH surge causes ovulation.
What happens in the luteal phase?
The leftover follicle becomes the corpus luteum, an endocrine gland, producing estrogen and progesterone. It will degenerate if fertilization does not occur and menstruation will result.
What causes the LH surge before ovulation?
an increase in estrogen
What hormone surges after ovulation?
progesterone
What happens in the theca cells?
LH promotes cholesterol conversion to testosterone.
What happens in follicle cells during the follicular phase?
Testosterone diffuses in, converting to estrogen, which helps develop the primary oocyte and grow the follicle cell.
What feedback mechanism results from low estrogen?
It inhibits FSH.
What feedback mechanism results from high estrogen?
It has positive feedback on LH production.
What feedback mechanism results from the combination of progesterone and estrogen?
They inhibit FSH, LH, and GnRH.
What form is the zygote when it attaches to the uterine lining?
blastocyst
What hormone is responsible for the secondary sex characteristics in the female?
estrogen
In the first 3 months of pregnancy, what hormones does the placenta synthesize and what are their roles?
- chorionic gonadotropin (CG) stimulates corpus luteum to make estrogen and progesterone
- chorionic somatomammotropin (CS) help mammory glands grow
In the last 6 months of pregnancy, what makes estrogen and progesterone?
the placenta
In the last 6 months of pregnancy, what hormone is no longer made?
chorionic gonadotropin (CG)
What are the individual cells called in blastula formation?
blastomeres
In a mature vertebrate, what are the parts of the coelom?
thoracic cavity and abdominal cavity
What is the blastocoel?
the fluid-filled cavity inside the blastula
What three layers form during gastrulation?
endoderm, ectoderm, and mesoderm
What is the ectoderm’s final differentiation?
skin, nervous tissue
What is the mesoderm’s final differentiation?
connective tissues, bones, muscle, blood
What is the endoderm’s final differentiation?
inner lining of digestive/respiratory tracts, major glands like liver and pancreas
What is formed during neurulation?
The ectoderm forms a neural tube which will become the nervous system.
What do neural crest cells form?
sense organs in the head, sensory cells, adrenal medulla
What is direct vs. indirect development?
Direct development involves care being given to the post-embryonic organism, while indirect development is when the organism is left on its own.
What is meant by a prepattern of development?
If an egg is separated at the right place (includes grey crescent), it will still form a complete embryo (2)
What is meant by developmental induction?
Certain tissues can direct the differentiation of neighboring cells to take on a fate they were not normally designed to fulfill.
What specifically forms the barrier between maternal and fetal blood, but allows diffusion?
chorion
In mammals, the formation of what structure marks the beginning of gastrulation?
primitive streak
What is meant by uterine quiescence?
whether or not it is receptive to embryo implantation
When does the uterus being to contract?
When there is a certain ratio of progesterone:estrogen
What is the role of oxytocin in parturition?
It induces contractions of uterine smooth muscle and produces prostaglandins which further induce contractions.
How is production of milk stimulated?
Suckling causes the hypothalamus to release prolactin releasing hormone (PRH), which causes the anterior pituitary to release prolactin, which causes the mammary glands to produce milk.
How is milk ejection stimulated?
Suckling causes oxytocin release from the posterior pituitary, which causes contraction of the myoepithelial cells of the breast.
