Reproductive Physiology 2

Sex determination

genetic sex

autosomal chromosomes

sex chromosomes

gonadal sex

gonadal specificity at wk 7

sex-determining region of Y-chromosome (SRY gene)

production of H-Y antigen, a plasma membrane protein in males only

phenotypic sex

sexual differentiation at wk 10-12

androgens induce male-type reproductive system

testosterone is the most potent

	Male	Female
Undifferentiated external genitalia	genital tubercle urethral folds genital (labioscrotal) swellings
genital tubercle	glans penis	clitoris
urethral folds	penis	labia minora
genital swellings	scrotum prepuce	labia majora
Reproductive tract	Wolffian ducts Müllerian ducts
Wolffian ducts	epididymis ductus deferens ejaculatory duct seminal vesicles	regress
Müllerian ducts	regress	oviducts uterus vagina

hCG stimulates fetal testis

testosterone induces development of Wolffian ducts

dihydrotestosterone (DHT) differentiates external genitalia

Müllerian-inhibiting factor cause regression of Müllerian ducts

feminization due to maternal sex hormones

sex-differentiation errors

failure of testes to develop or produce testosterone

deficiency in 5 a-reductase

adrenal production of dehydroepiandrosterone (DHEA)

androgenital syndrome

female pseudohermaphroditism

precocious pseudopuberty

Immunological aspects of pregnancy

endometrium as privileged site

trophoblast

only the extraembryonic trophoblast interfaces with maternal tissue

trophoblast membranes do not express polymorphic form of
class I or class II transplantation HLA antigens

some monomorphic class I antigens are found on cytotrophoblast, but no class II

trophoblast membranes are not, however, antigenically inert

both B- and T-lymphocyte activation by trophoblast antigens

early step in generation of cytotoxic reactions in cell-mediated
immunity is allogeneic recognition

blocking of allogeneic recognition by B cell-produced antibodies to
trophoblast can inhibit T cell activation

TLX (trophoblast lymphocyte cross-reactive) antigens

normal pregnancy requires maternal immunological recognition of TLX antigens
inherited by conceptus

Factor	Primary aborting couple	Childbearing couple	Secondary aborting couple
TLX	same as mother	differs from mother	differs from mother
blastocyst	not recognized	recognized	recognized inappropriately
protective response	inadequate	present	blastocyst rejected
pregnancy	aborted	successful	aborted

trophoblast antigens

TA1 group

primarily protein with some carbohydrate

normal immune response to TA1 causes a specific allogeneic inhibitory effect

TA2 group

primarily carbohydrate with some protein

Fate of the blastocyst
Maternal TLX-1,2		Paternal TLX-1,3
		1	3
	1	1,1 aborted	1,3
	2	2,1 aborted	2,3

Fate of the blastocyst for primary aborting couples
Maternal TLX-1,2		Paternal TLX-1,2
		1	2
	1	1,1 aborted	1,2 aborted
	2	2,1 aborted	2,2 aborted

Summary:

Together, the TA1 and TLX antigens may function in normal pregnancy by inducing
maternal production of antibodies that block the immune response to TA1. Thus, absence
of TLX antigen recognition due to sharing of maternal-paternal TLX antigen profiles may
not allow anti-TA1 activity and may lead to subsequent fetal rejection

Fertilization

occurs in the ampulla of the fallopian tube [oviduct]

penetration of corona radiata and zona pellucida

sperm fertilin binds with egg integrin to allow sperm to enter

species-specific

block to polyspermy

results of fertilization: the conceptus

zygote ® morula ® blastocyst

cytotrophoblast and syncytiotrophoblast

inner cell mass [embryoblast]

implantation

ectopic pregnancies

decidua and placentation ¹

prostaglandin secretion

placenta formation

chorionic villi

umbilical vessels

Hormones in gestation

human chorionic gonadotropin ²

estrogen

principally estriol

progesterone

human chorionic somatomammotropin

gestational diabetes ³

relaxin

placental PTHrp

oxytocin

prolactin [enzyme synthesis, but not milk production]

Hormones in lactation ⁴

PIH/PRH

prolactin

oxytocin

Go to beginning