Gyn-Ics-5-Gamete Transport, Fert, & Implantation

Front 1

what are the 3 segments of fallopian tubes

Back 1

Each fallop tube consists of a hollow tube of SmM (myosalpinx) with inner lining of mucosa (endosalpinx). The tube ihas an outer sheath (mesosalpinx=part of broad ligament).Thus, endosalpinx is innermost; mesosalpinx is outermost.

1. myosalpinx
-hollow core of smooth muscle
-3 layers: inner long layer, prominent middle circular layer

2. endosalpinx
-the inner lining of mucosa that lines in the inner part of myosalpinx (smooth muscle)
-prox part of tube (near uterus): secretory cells
-distal part of tube (near ovary): ciliated cells (makes sense b/c cilia sweep sperm from fallopian tube toward ovary)
3. mesosalpinx (outermost)
-ensheaths & protects the fallopian tube
-part of the broad ligament, so maintains nl anatomic rel'n to other pelvic viscera

Front 2

Fallopian tube subdivisions

Back 2

*see picture i saved on my computer

From proximal (near uterus) to distal (naer ovary):

1. intramural or interstitial segment
-@ jxn of tube and uterus
-controls passage of spermatozoa into tube (sperm goes from uterus-->ovary for fertilization in ovary) and entrance of embryo into uterus (embryo goes from fallopian tube-->uterus)

2. isthmus
-most densely muscular segment of tube
-secretory cells

3. ampulla
-longest segment
-ciliated (cilia sweep/"PULL" [amPULLa] sperm from tube-->ovary)

4. infundibulum

Front 3

ejaculation

Back 3

2 phases:
1. seminal emission ("pre-cum"): oozing of sperm-rich fluid out of tip of penis

2. ejaculation proper

Front 4

barriers to sperm transport in female

Back 4

1. vagina is acidic (vs. sperm-alkaline)
2. cervical mucus is thick and sperm cannot pass when estrogen levels are low (estrogen levels are high during ovulation-->mucus is thin and sperm can pass)

3. uterotubal jxn=barrier to sperm ascent

Front 5

transport of sperm in fallopian tube:

Back 5

1. Rapid transport (no fert):
a few spermatozoa transported to ampulla within a few minutes of intercourse, but no fertilization

2. Fertilization: sustained colonization of proximal isthmus, where sperm remain til ovulation

Front 6

when does ovulation occur?

Back 6

spontaneously 16-39 hours after the LH surge

Front 7

where in fallopian tube is ciliary activity greatest?

Back 7

in fimbriae (=fingers, closest to ovum), intermediate in ampulla, and lowest in isthmus (farthest from ovum);

makes sense b/c cilia sweep sperm into the ovum

Front 8

where in fallopian tube is secretory activity greatest?

Back 8

isthmus (makes sense b/c isthmus is closest to cercix and cervix has lots of mucus)

Front 9

Time course of oocyte/embryo transport thru fallopian tube (Objective 2)

Back 9

-Human egg and embryo spend 80 hrs within tubal (fallopian tube) lumen. Most of time is spent in ampulla, and passage thru isthmus (near cervix) is very rapid.
-Embryos enter uterus at 7-12 cell stage

Front 10

maturation of spermatozoa

Back 10

spermatozoa cannot move well or fertilize ova. They gain these abilities while passing thru epidydmis (when then they become sperm):

1. they get cAMP==>sperm tail can beat

2. acquire strong disulfide bonds in sperm head and tail

Front 11

sperm capacitation (Obj #3)

Back 11

"capacitation"= the sperm's acquisition of ability to fertilize the egg

Front 12

acrosome rxn

Back 12

The acrosome reaction is the reaction which occurs in the acrosome of the sperm as it approaches the zona pellucida.

As the sperm approaches the egg, the membrane surrounding the acrosome fuses with the plasma membrane of the sperm, exposing the contents of the acrosome==>acrosomal enzymes penetrate the zona pellucida==>sperm can fuse with ovum

The fertilizing spermatozoan initiates the true acrosome rxn when it contacts the zona pellucida (the last physical barrier that the spermatozoon must pass before fertilizing the ovum)

Front 13

blocks to polyspermy

Back 13

(ovum) cortical granule exocytosis=granules of ovum cortex release their contents. This process prevents ovum from being fert by multiple sperm, b/c this process alters the following structures (thus preventing add'l sperm from binding to them):

1.zona pellucia (via zona rxn)
2.oolemma (via plasma membrane block)

Front 14

what is considered the end of fertilization and the beginning of embryonic development

Back 14

syngamy (mingling of chromosomes derived from both parents)

Front 15

when does first cleavage occur?

Back 15

12 hrs after syngamy

Front 16

morula

Back 16

solid ball of cells (b/c blastomeres develop tight jxns); b/w 8-16 cell stage.

soon after this, conceptus enters endometrial cavity

Front 17

at what stage does conceptus enters endometrial cavity

Back 17

soon after morula stage

Front 18

major stages of implantation

Back 18

1. Dissolution of zona pellucida
2. Blastocyst Hatching:
-Blastocyst frees itself from zona.
-This results from proteolytic enzymes of trophectodermal origin acting upon zona in concert with expansion of developing blastocyst
==>zona thins and tears
==>extrustion of blastocyst

3. Trophectoderm and luminal epithelium (of endometrium) establish physical contact and become firmly adherent. 2 Phases:

A. Apposition
-conceptus can be dislodged w/o damage

B. Adhesion
-primitive junctional complexes b/w trophoblast and epithelial cells establised

4. Embryonic Signals
-embryo sends short-range signals to mom to indicate pregnancy
5. Decidualization
-various changes, incl increased vascular permeability in uterine stromal tissue underlying the conceptus; edema; changes in stromal cell morpholog
-imp for supplying nutrients to conceptus, facilitation of placental info, and limiting invasiveness of trophoblast

6. Trophoblastic Invasion
-trophoblast invades==> destroys stromal cells, CT, and maternal bv walls

7. Early Placentation
-trophoectodermal cells differentiate into:
a. syncytiotrophoblast:
-noncellular, multinucleated;
-primitive, invasive tissue

b. cytotrophoblast
-generates more trophoblastic cells
-2 fxns:
i. invade maternal tissue to anchor placentra and provide bl flow to fetus
ii. form syncytiotrophoboalst req for gas/nutrient exchange

Front 19

major fxns of trophoblast

Back 19

2 major fxns:
1. invade maternal tissue to anchor placenta and provide bl flow to fetus

2. form syncytiotrophoblast req for gas/nutrient exchange