anatomy

Question 1

fertilization and development (1)

Answer 1

Sperm travels towards ovum (remem. lots of nutrition from uterine tubule cells = food + peg cells
help with capacitation [weaken acrosomal membrane])

Question 2

fertilization and development (2)

Answer 2

 ~200 reach egg-need to penetrate corona radiata (follicular/granulosa cells that protect ovum during
egestion from ovary)

Question 3

fertilization and development (3)

Answer 3

 acrosomal release of enzymes ‘pops’ follicular cells-leaves gap to surface of ovum (zona pellucid =
microvilli + glycoprotein matrix)

Question 4

fertilization and development (4)

Answer 4

 have to have an intact acrosomal cap to get thru zona pellucid b/c those enzymes eat thru matrix +
flagellum to move inward

Question 5

fertilization and development (5)

Answer 5

 receptor on interior acrosomal membrane matches receptor on surface of ovum membrane = fusion
of sperm & ovum mems

Question 6

dont want polyspermy so fusion results in

Answer 6

1) rapid depolarization (Na+ influx) across ovum from point of fusion (short term; ‘shock’)
this causes

2) Ca++ release from endoplasmic reticulum → granules released from packets at cell membrane →
react w/glycoprotein matrix-hardens up (epoxy) + destroys binding receptors (long term)

Question 7

sperm drawn in a cell results in

Answer 7

use nucleus + centriole; degrade all else

Question 8

fusion also results in

Answer 8

triggering ovum to complete meiosis II:
Nuclei enclosed in membranes = pronuclei;
 chromos. replicate; membranes dissolve;
 chromos line up b/w mitotic spindles (just like mitosis);
 go thru anaphase & telophase → divides into 2 cells each w/ 2n = blastomeres
 process complete ~ 30 hours after fusion (ovulation 1-2 days ago)

Question 9

meiosis II results in

Answer 9

2 cells same size as ovum

Question 10

gestation

Answer 10

(prenatal development): 40 weeks
usu. counted from 1st day of last menstrual period even tho 1st two weeks are prior to ovulation = no
pregnancy yet!

Question 11

gestation (1st trimester)

Answer 11

pre-embryo → embryo → fetus

Question 12

gestation (2nd trimester)

Answer 12

dev. of organs/organ systems

Question 13

gestation (3rd trimester)

Answer 13

↑ size of offspring & get fat

Question 14

order

Answer 14

ovum + sperm → 2 blastomeres → morula → blastula → blastocyst (inner cell mass + outer trophoblast)
(16 cells) (hollow ball)
new organism chorion
+ membranes + placenta

Question 15

blastocyte implants into

Answer 15

endometrium

Question 16

2 types of outer trophoblasts

Answer 16

1) syncytial: cell mem. bd → spreads into endometrium (enz)
2) cellular: next to inner cell mass

Question 17

By day 10

Answer 17

post-fertilization, endometrium grows over blastocyst
 syncytial trophoblast: keeps enlarging/spreading
1) destroys endometrial glands = release nutrients (fuels ÷)
2) destroys capillary walls & creates lacunae (blood pools in)
 cellular trophoblast: surrounds lacunae: gets nutrients from maternal blood for developing embryo

Question 18

day 12

Answer 18

start gastrulation (p. 1111)
(still haven’t ‘missed’ your period)
 outer layer = ectoderm
 inner layer = endoderm germ layers → diff. tissues
 middle layer = mesoderm