Diagrams Flashcards
Role of interstitial cells
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Functions of testosterone
Stimulate the male pattern of fetal development
Initiates maturation of the male reproductive organs
Maintains male reproductive organs in their nature and functional state
Responsible for the sex drive (libido)
-> in both males AND females (adrenal glands)
Stimulates spermatogenesis (along with androgen binding protein)
Anabolic on muscle and bone tissue
Stimulates an increase in the rate of bone production at the epiphyseal plates (responsible for the growth spurt in boys during adolescence)
Causes the development of male secondary sex characteristics - these are features included in non reproductive organs by this hormone
- stimulates the appearance of pubic, axillary, and facial hair
- causes an increase in size and density of bone
- increased growth of body hair
- stimulates enlargement of the larynx, causing a deepening of the voice
- stimulates increased sebum production in sebaceous glands
- causes an increase in the production of muscle proteins leading to increased size and mass of skeletal muscles
Responsible for male pattern baldness, in combination with hereditary factors
Indirectly increases red blood cell production via increased secretion of erythropoietin by the kidneys
Role of Sustentacular cells
Generally support spermatogenesis (referred to as “nurse cells”)
Form the blood testis barrier -> prevents antigens from the later stages of spermatogenesis from seeping into the bloodstream, and thus prevents immune system attack of spermatogenic cells
Provide nourishment for spermatogenic cells
Secrete Testicular fluid - the medium in which Spermatocyte life within the testes, epididymis, and vas deferens
Absorb the excess cytoplasm lost during spermiogenenis
Secrete androgen binding protein (ABP) - keeps the concentration of testosterone high in the vicinity of spermatogenic cells, required for spermatogenesis
Secrete inhibin
Secrete Müllerian duct inhibiting factor (MIF)
Functions of estrogens
At and after puberty
Causes maturation of the female reproductive organs, maturation of the internal reproductive organs, maturation of the external genitalia
Stimulates the maturation of ovarian follicles
Stimulates hair growth
- body hair becomes more coarse
- stimulates growth of axillary and pubic hair
Anabolic on muscle and bone
- stimulates the growth spurt seen at puberty in females
- increases the production of muscle protein in skeletal muscles
Enhances calcium deposition in bone
Causes an increase in the ratio of HDLs/LDLs
-> cardio sparing effect
Causes the appearance of secondary sex characteristics in women
- widening of the pelvis
- deposition of adipose tissue in the beasts
- female pattern of adipose distribution body wide
Functions of progesterone
Uterine support during pregnancy
- quiets the myometrium-prevents premature contractions
- maintains vascularity of the stratum functionalis, keeping it intact throughout gestation
- fights against gestational hypertension -> vasodilation and diuretic effects
- inhibits T cell attack of fetal tissue during gestation
Dual effects of estrogen and progesterone
Establishment of the ovarian and uterine cycles
- both hormones directly involved in the feedback loops within the ovarian cycle
- cycling of hormone levels causes the stratum functionalis to be alternately shed and regrown (menstrual cycle)
Preparation of the breasts for lactation (during pregnancy)
Involved in the initiation of parturition (childbirth)
Events involved in meiosis diagram explained
** look at visual meiosis diagram **
First half not noted* -> use with visual diagram
Note:
- this is they key type of cell division involved in gametogenesis
- 4 daughter nuclei are produced -> one mother cell provides 4 sperm cells
- the chromosomes in the 4 resulting nuclei are “mixed up”, containing unique combinations of recombinant and parental chromosomes
- this causes tremendous variation in the genetic make up of gametes and thus offspring
- the chromosome number is cut in half (1n)
Developmental biology catch up notes (day 7)
Implantation if blastocyte -
- the blastocyte makes contact with the stratum functionalis about 7 days after fertilization
- upon doing so, the trophoblast cells differentiate into two cell populations:
- ) the cytotrophoblast - remains the outer sphere of cells surrounding the inner cell mass
- ) the syncytiotrophoblast - a spreading multinucleate mass that secretes hyaluronidaise, an enzyme that digests the connective tissue of the stratum functionalis, causing the blastocyst to “eat it’s way” into the endometrium
Implantation is complete by day 14, by which time the inner cell mass has begun differentiation
Developmental biology catch up notes (day 8-10)
Bilayered embryonic disc
Developmental biology catch up notes (day 10-20)
Gastrulation
- the series of cell migrations that concert the embryonic disc into an embryo composed of the three primary germ layers. The primary germ layers are differentiated cells, destined to give rise to the following tissues:
Ectoderm - epidermis of the skin and all of the nervous system
Endoderm - epithelial linings of open body cavities (respiratory, urinary, GI, reproductive) and associated glands
Mesoderm - all CT, all types of muscle, endothelium, all of the cardiovascular system
Also formed during gastrulation are the extra-embryonic membranes, all of which are partly composed of mesoderm:
Yolk sac -> endoderm and mesoderm - forms embryonic blood cells and primordial germ cells
Allantois -> endoderm and mesoderm - forms part of the umbilical cord and urinary bladder
Amnion -> ectoderm and mesoderm - surrounds the fetus and is filled with amniotic fluid
Chorion -> trophoblast and mesoderm - outermost membrane, surrounds all other membranes and forms the fetal portion of the placenta
Placentation
Formation of the placenta
- chorion
- amnion
- chorionic villi
- intervillious spaces
- maternal blood
- capillaries in villi
- BV’s in chorion
- umbilical arteries
- umbilical vein
- umbilical cord
- yolk sac
Developmental biology catch up notes (stratum functionalis)
Decidua basalis
- stratum functionalis that forms the maternal part of the placenta
Decidua capsularis
- stratum functionalis that forms a capsule around the amnion/fetus
Developmental biology catch up notes (placenta - secretes hormones: the endocrine placenta)
The endocrine placenta:
It secretes ->
Progestins
- keeps stratum functionalis intact during pregnancy, quiets the myometrium, inhibits T cell attack of fetal tissue
Estrogens
- stimulate production of myometrial oxytocin receptors
- near term - irritate myometrium -> contractions
Relaxin
- loosens pelvic ligaments
Placental prolactin, placental lactogen, estrogen, progesterone, prolactins
—-> prepare breasts for lactation
Developmental biology catch up notes (parturition)
Occurs because of an interaction between physical and hormonal factors
Near term:
- decrease in prog, increase in estrogen secretion - irritates the uterus - spontaneous contractions
- placenta secretes prostaglandins -> spontaneous contractions
- catecholamine from adrenal gland - spontaneous contractions
Initial contractions kick off a positive feedback loop that culminates in childbirth. This involves the hormone oxytocin, which causes contraction of the myometrium, as well as the myoepithelial cells of the mammary glands and male prostate
Visual placenta diagram
