Animal Reproduction and development
From speech of Aristophanes:
...The sexes were not as they are now...the primeval man...had four hands
and four feet, one head with two faces...Terrible was their might and strength...and
they made an attack upon the gods...Zeus...said: "Methinks I have a
plan which will humble their pride and improve their manners; men will continue
to exist, but I will cut them in two...After the division of the two parts
of man, each desiring his other half, came together, and throwing their
arms about one another, entwined in mutual embraces, longing to grow into
Love (sweet Chloe) is a god, a young Youth, and very fair, and wing'd to
flye... His power's so vaste, that that of Jove is not so great... For there
is no med'cine for Love, neither meat, nor drink, nor any Charm, but only
Kissing, and Embracing, and lying naked together.
-Daphnis & Chloe By Longus Translated out of Greek by George Thornley
Audesirk, Audesirk & Byers Chapter 40
Today's musical selection
Bob Dylan Lay
Meiosis and sperm
Spermatogonia (mitosis and meiosis) - primary spermatocytes
- meiosis (both divisions) - spermatids (scrotum cooler)
Sperm (meioses throughout adult life) Seminiferous tubules
300 million/ ejaculation
Testes - seminiferous tubules make sperm, stimulated by FSH, inhibin for
Interstitial (Leydig) cells produce testosterone, stimulated by LH (ICSH),
Low mag section of testis, higher mag showing seminiferous tubule and interstitial
Testes in short
day hamsters are smaller than in long day hamsters
Bulbourethral (Cowper's) gland (early overflow from sexual excitement)
Seminal vesicle - fructose, amino acids, mucus, prostaglandins (uterine
Prostate - alkaline (infection, cancer most men > 50)
Capacitation of sperm
Vas deferens - peristalsis -(vasectomy 100% effective- permanent long term
Urethra (of course, it is output here for which condom is a form of contraception)
summary of birth control
Many sperm attack one egg, only one fertilizes - fast (electrical) response
acrosome, nucleus, mitochondria (not go into egg), flagellum
Parasympathetic arterioles (unique, usu only symp.) - erection (sleep)
ACh - NO - smooth muscle dilate- viagra blocks breakdown enzyme
NO synthase in cavernous artery and corpus cavernosum
Robert F. Furchgott, Louis J. Ignarro, Ferid Murad Nobel
1998 "for their discoveries concerning nitric oxide as a signalling
molecule in the cardiovascular system"
Sympathetic - ejaculation inhib erection
Here is the typical text book diagram depicting the menstrual (ovarian)
For convenience, use the term "eggs" earlier, now I get more official
Meiosis, ovary, steroids
primary oocyte in early follicle
secondary oocyte in mature follicle
FSH from anterior pituitary causes follicle to release estrogen
LH from anterior pituitary induces ovulation and conversion to the corpus
luteum that secretes progesterone
Here's how that relates to meiosis
Primary oocyte (2-4 million at birth, 1st meiotic prophase)
(400,000 at puberty, only 400 used)
(no oogonia after 3 mo)
Secondary oocyte + polar body
(Graffian follicle finish 1st meiosis) ovulation
if 2 ovulations - DZT - 2 amnions, 2 chorions
twins 1.2% of births, of these 70% "fraternal"
DZT run in family
Questions used in 2007 and 2008 related to this outline
What is not true about the "egg" at the time of ovulation?
(a) It comes from the mature follicle.
(b) It is near the fimbriae of the uterine tube.
(c) It is called a secondary oocyte.
*(d) Meiosis is complete.
(e) Its release followed a surge of LH.
A polar body is
(a) the cell that gives rise to the primary oocyte.
(b) the tissue that makes progesterone.
(c) the portion of the blastocyst that will turn into the embryo.
(d) the hollow space in the blastocyst.
*(e) the discarded nucleus of meiosis.
The "lining" (inside layer) of the uterus is called the
What hormone from the anterior pituitary starts the further development
of the primary follicle?
What produces testosterone?
*(a) interstitial (Leydig) cells
(c) the bulbourethral (Cowper's) gland
(d) beta cells of the islets of Langerhans
(e) the posterior pituitary
When (or where) is meiosis complete for the human "egg?"
(a) in the ovary before birth.
(b) in the primary follicle.
(c) in the blastula after cleavage divisions.
(d) in the secondary oocyte just when ovulation occurs.
*(e) when sperm attach in the oviduct.
What is the acrosome?
(a) a pancreatic neurosecretion
*(b) an packet of enzymes on the sperm cell
(c) an antigen
(d) the cavity in the blastyocyst
(e) a hormone from the adrenal medulla
The birth control pill blocks
(a) buildup of the endometrium.
Which is male?
A) corpus luteum
B) polar body
What are dizygotic (fraternal) twins?
A) when two ovaries are fertilized
*B) when two eggs are fertilized
C) when two follicles are fertilized
D) when one zygote splits into two
E) the same as monozygotic (identical) twins
Nitric oxide (NO)
A) functions as a feedback signal to the hypothalamus.
*B) functions to mediate erection.
C) functions to maintain the corpus luteum.
D) is one of the glandular components of semen.
E) is secreted from the chorion.
Where does estrogen come from?
A) the interstitial cells
B) the adrenal cortex
C) the posterior pituitary
*D) the follicle
E) the hypothalamus
Why is cGMP relevant to reproduction?
(a) It is a gonadotropin
(b) It is secreted by interstitial cells.
(c) A surge in cGMP induces ovulation.
*(d) It is involved in erection.
(e) It provides a feedback signal to inhibit FSH secretion.
A ligation is used in a tubal ligation and what other operation?
*(c) a vasectomy
(d) an IUD
(e) in vitro fertilization
How is the autonomic nervous system involved in reproduction?
(a) It triggers ovulation.
*(b) The parasympathetic portion increases blood flow to the corpus cavernosum.
(c) It controls meiosis in the male but not in the female.
(d) It controls estrogen secretion by the corpus luteum.
(e) Gastrulation causes the formation of 3 layers, one of which is the autonomic
The word for the final product of meiosis which is fertilized by the sperm
nucleus is the
(c) polar body.
Which is female?
C) bulbourethral gland
D) interstitial cells
If fertilization occurs, what keeps the wall of the uterus from breaking
*A) progesterone enabled by a hormone from the chorion
B) pituitary steroids
C) hypothalamic gonadotropins
D) the amnion
E) the secondary oocyte
The rhythm method
A) relies on inhibiting FSH and LH.
B) is also called a tubal ligation.
C) is also called a vasectomy.
*D) depends on knowing that there are only a few days per month when intercourse
can lead to pregnancy.
E) is made possible by potentiating nitric oxide action by inhibiting cGMP
When is meiosis complete in the female?
A) at birth.
B) in the primary oocyte.
*C) at the time of fertilization.
D) at puberty.
E) Meiosis is never complete in the female.
What are monozygotic (identical) twins?
A) when two blastocysts implant
*B) when the inner cell mass divides into two
C) when two eggs are fertilized
D) the same as dizygotic (fraternal) twins
E) when the placenta divides into two
Where does follicle stimulating hormone (FSH) come from?
A) the chorion
B) the hypothalamus
*C) the anterior pituitary
D) the corpus luteum
E) the testes
Where does fertilization take place?
A) the ovary
B) the endometrium
C) the vas deferens
D) the follicle
*E) the uterine tube
Questions used in 2002 relating to this outline (and other outlines)
Ovulation is triggered by a surge in
(a) a steroid from the posterior pituitary.
(b) a prostaglandin from the hypothalamus.
*(c) a peptide from the anterior pituitary.
(d) a steroid from the ovary.
(e) a peptide from the chorion.
Where would you find the acrosome?
(a) in the hypothalamus
*(b) on a sperm cell
(c) on an antigen
(d) in the chorion
(e) in the pancreas
Which does not contribute substances to semen?
(a) seminiferous tubules
*(b) interstitial cells
(d) bulbourethral gland
(e) seminal vesicles
The birth control pill blocks
(a) buildup of the endometrium.
This page was last updated 8/20/09
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