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Lecture 7

BIOLOGY 321 Lecture Notes - Lecture 7: Body Plan, Prophase, OrgasmPremium

5 pages65 viewsSpring 2017

Department
Biology
Course Code
BIOLOGY 321
Professor
Dr.Drea
Lecture
7

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Primate Sexuality
Continuation of Lecture on Male Anatomy…
I. Evolution of Male Genetalia
a. Lock and key hypothesis: specialized structures as a species isolating mechanism; enables
a “proper fit” so that species can’t incorrectly mate
b. Genitalic recognition hypothesis: fertilization occurs only if appropriate copulatory
stimulation; the F regonizes the M
i. This might be important with closely related subspecies
c. Pleiotropism: control of several phenotypic features by single gene aka a side effect,
accident of evolution
d. Mechanical conflict of interest: structures are necessary to bypass female barriers
i. If female evolves longer reproductive tract for cryptic choice, a male has to evolve
a longer penis
ii. Male structures imposed upon them by selection from female anatomy
e. Sexual selection:
i. F choice (internal courtship device)
ii. M-M competition: penile morphology may contribute to improved sperm
competition (especially penile spines)
II. Sexual Selection of Penile Morphology
a. Is bigger better? it depends
i. When M-M physical competition is important, body size is much more dimorphic;
when there is less outward aggression, testes and penile size are greater
b. Female view of males:
c. Penile Morphology & Mating Systems:
i. When females are more monogamous and polygamous, tned to see:
1. Smaller, shorter penis
2. Unspecialized/adorned penis
3. Copulate less often maintain erection less frequently smaller
bulbocavernosus muscle
4. Ejaculate less often semen produced in smaller volume, smaller less
elaborate seminal vesicles
ii. MM MF, Dispersed:
1. Elongated penis
2. Lots of specializations
3. Copulate often larger BC muscle
4. Intromission maintained post ejaculation aka literally keep penis in
longer, need longer erection os penis
5. Ejaculate often more semen larger, more lobulated seminal vesicles
Female Reproductive System (women as example)
- Simians: single chambered uterus, prosimians: y-shaped or bicornuated uterus
o Related to type of placentation and number of offspring
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I. Functions
a. Ovaries
i. Production of f reproductive cells, oogenesis
ii. F horomone production (estrogen & progesterone): involved in secondary sex
character
1. males also have these, but in lower quantities
2. function as an endocrine gland
b. Uterus
i. Reproduction:
1. conduit for sperm transport
2. site for implantation of fertilized ova
3. placentation
4. growth and development of fetus
5. parturition: birth
c. vagina:
i. receptacle: receiving penis and sperm
II. Female Pubertal Changes
a. Secondary Sex character
i. Growth of reproductive organs, menstrual cycle
ii. Behavior: nurturing
iii. Breast development
iv. Female body form: rounded hourglass
v. Hair distribution pattern
b. All due to the distribution of estrogen target cells throughout body
III. Internal Reproductive Organs
a. Uterus: above and behind bladder; thick walled, muscular, 7.5cm long
i. Capable of incredible expansion due to smooth muscle lining the uterus
ii. Cause orgasm (helps propel sperm), cramps (sheeding
b. Ovaries: 3 cm long, just above the uterus, a pair
i. Basically a mass of oocytesthe cells from which eggs develop
ii. Held in place by ligaments
c. Vagina: often differentiated between lower and upper part
d. Fallopian tube or oviduct: link the ovaries to the uterus
e. Fimbria: at the end of the oviducts, finger-like projections that come into close contact
with the overus in order to help coerce the eggs into the oviduct
f. The opening into oviduct is the ostium; lined with cilia to propel the egg into oviduct
i. It is possible for the egg to NOT end up in the oviduct
ii. This plus fimbria are structures to help “catch” the egg, forms a wider, open end
g. Isthmus: thin proximal end of the oviduct
h. Uterotubual junction: where the oviduct meets the uterus
i. Very narrow and convoluted
ii. An area/roadblock for a female to block sperm
i. Endometrium: lining layer of the uterus
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