What I don't know

Question 1

What sperm and egg contributes to conceptus

Answer 1

Sperm: Centriole and pericentriolar material to form the centrosome.
Egg: Cell membrane, cell organelles, macromolecular matrix on which centrosome and chromosomes operate. Maternal cytoplasmic inheritance.

Question 2

Testes organisation

Answer 2

Extratubular compartment consists of a vascular component in free communication with an interstitial component, which includes the lymphatics, and in which androgen synthesis occurs in Leydig cells.

Question 3

Afterbirth

Answer 3

Placenta and foetal membranes that are expelled from the uterus following the baby’s birth

Question 4

Villi late gestation

Answer 4

At about 20 weeks, the villi have regressed to one pole to form the discoid placenta. The placenta membranes remain in regions where the villi have regressed and when ruptured, provide an exit route at birth.

Question 5

Embryonic vs Foetal period of development

Answer 5

Embryonic period of development: 0-8 weeks post-fertilisation when organ differentiation happens. Very susceptible to ROS and alcohol. Most deaths happen during this period.

Foetal period of development: 9-38 weeks. Major growth phase.

Question 6

Placental blood volume

Answer 6

Mature placenta contains 150ml of maternal blood, and this volume is replaced 3-4 times every minute.

High volume, low velocity, low pressure.

Question 7

Erection

Answer 7

Inflow and outflow of blood is ABSENT.

Question 8

Maternal metabolism

Answer 8

EARLY pregnancy: Appetite increased, net deposition of nutrient resources.

Question 9

Pre-eclampsia

Answer 9

De novo hypertension of 140/90 mmHg starting
after 20 weeks of gestation, proteinuria, oedema
Only seen in humans
Most common with 1st pregnancies with a particular partner.
Due to abnormal placenta, so complete hydatidiform moles can cause PE.
High risk in placenta formed from donated oocyte.

Question 10

Hormones that control maternal metabolism

Answer 10

5P LORA

Progesterone, hPL, prolactin, PGH, PAPP-A, leptin, oestrogen, relaxin, and Adrenal cortical hormones

Question 11

Foetal determination of foetal growth

Answer 11

GESI

genome, endocrine, sex, infection

Question 12

Maternal determination of fetal growth

Answer 12

SUNPED

Socioeconomic, uterine size, nutrition, parity, environmental, disease

Question 13

Foetal physiology

Answer 13

ORCOF

Oxygen affinity, resetting of reflexes, closure of shunts, overall resistance and fetal response to hypoxia.

Question 14

Lactation

Answer 14

From puberty onwards, oestrogen + progesterone + GH cause mammary gland growth. GH acts via IGF1.

Early in a pregnancy, oestrogen + progesterone + hPL causes further mammary gland growth.

Late in a pregnancy, GH initiates milk production. But milk production can only occur if oestrogen + progesterone + hPL decrease.

Milk production/galactopoiesis is maintained by prolactin, which is elevated by suckling.

Oxytocin is needed to squeeze milk out by inducing contractions of the myoepithelial cells around the alveoli.

Question 15

Partuition

Answer 15

Placental CRH acts at 2 levels: Foetal pituitary and foetal adrenals, to increase 2 things: DHEAS production and cortisol production.
Placental CRH production also increase maternal CRH levels.
Placental CRH production inhibited by progesterone and stimulated by catecholamines (from lecture notes) and cortisol

DHEAS makes more oestrogen which does 3 things: Increased PLA2 activity, oxytocin receptor density, actin + myosin filaments.

Cortisol does 2 things: Increased COX activity, decreased PGDH activity.

Note that CRH can inhibit contractions by increasing cAMP in myometrium (from lecture notes).

Question 16

Aneuploidy stats

Answer 16

Accounts for:
50% of spontaneous miscarriages
5% of still births
0.5% of live births have a high level of genetic abnormalities including

For live ones, you can see either: error of ploidy, error of somy, translocations, genetic mosaics.

Question 17

Miscarriage lecture

Answer 17

Look at hCG levels. From the time you can detect hCG increases, percentage of pregnancies that result in pregnancy loss is 35%. 20% of those is from the initial detection of hCG to the time when people normally have a clinical test for pregnancy (which looks for slightly higher hCG levels). 15% is from clinical test time to birth.

Question 18

Neonatal physiology hormones

Answer 18

Beta adrenoceptor and Na+ channel expression increased by cortisol.
Cl- channel inhibition mediated by catecholamines.
Thyroid hormone is also needed to absorb lung liquid.

Beta adrenoceptors are also needed for surfactant production. Since cortisol directly increase surfactant production by OLB, cortisol directly and indirectly increases surfactant production.

Brown fat activity increased by thyroid hormone and catecholamines.

Increase in arterial PO2 in neonates helps to close ductus arteriosus and venosus.

Oestrogen and prolactin needed to induce maternal care behaviour.

Question 19

Premature birth (before 35 weeks)

Answer 19

Respiratory distress syndrome
Wet lung syndrome
SIDS due to failure or resetting of thyroid axis, baroreceptors, chemoreceptors.
Immature neural mechanisms due to lack of T3.
Hypothermia (premature babies have greater SA:V ratio, less brown fat).

Give dexamethasone or betamethasone.

Question 20

Why IUGR leads to increased cardiovascular disease

Answer 20

Premature activation of HPA axis leads to inappropriate pattern of growth for a stage of development.
Epigenetic programming of stem cells.
Underdeveloped organs.

Question 21

Rhythms

Answer 21

Ultradian rhythm: Cycle lasts less than a day.
Circadian rhythm: Cycle once a day.
Infradian rhythm: Cycle lasts more than a day.

Question 22

Chlamydia

Answer 22

Most prevalent STI in the UK.

Question 23

Barker hypothesis

Answer 23

“The aetiology of many chronic diseases lay not
only in genetic predisposition or in adult lifestyle but also in the ways in which early life events could affect subsequent biology”

In exam: IUGR leads to increased risk of cardiovascular diseases.

Question 24

Inhibin’s role in male gametogenesis

Answer 24

As Sertoli cells are implicated in the support of spermatogenesis, as well as being the site of inhibin production, it appears that inhibin serves as the measure of spermatogenic effectiveness.

Inhibin increases androgen production by Leydig cells in response to LH.
Prolactin also increases androgen production by Leydig cells in response to LH.

Remember that androgens not only cause Sertoli cells to make oestrogen, but also nurtures and stimulates Sertoli cells.

Question 25

Dominant follicle

Answer 25

retarded follicles show low levels of inhibin but higher Retarded follicles show levels low inhibin and high activin levels. Activin attenuate androgen output by the theca, thus indirectly suppress both inhibin synthesis and oestrogen output (activin does the same to leydig cells). Thus, dominant follicles are characterized by high ratios of both inhibin : activin and IGF : IGFBP, and lots of PAPP-A. Retarded follicles show the reverse.

Activin lowers androgen output!
Activin also enhances FSH output at the pituitary.
Activin direct opposite to inhibin.

Question 26

Sertoli cells

Answer 26

Sertoli cells form a continuous epithelial sheet, sealed with tight junctions, attached to the basement membrane of the seminiferous tubule.
The nuclei are located on the basement membrane of the seminiferous tubules.

Spermatogonium –> primary spermatocyte –> secondary spermatocyte –> spermatid –> spermatozoon.

Question 27

Epididymis

Answer 27

Epididymis is lined by pseudostratified columnar or cuboidal epithelium containing a layer of principal cells and smaller basal cells.
Apical edges of the principal cells form stereocilia
which are non-motile structures.
Outside the epithelium is connective tissue and smooth muscle. More smooth muscle towards cauda epididymis.

Question 28

Seminal vesicle

Answer 28

Paired structure. Highly invaginated inner surface.
Epithelium same as epididymis.
Secretes alkaline fluid under sympathetic stimulation. Contains fructose, prostaglandins, fibrinogen-like proteins.
Outside the epithelium is connective tissue and smooth muscle.

Question 29

Prostate

Answer 29

Large. Consists of many tubules each with their own lumen. Columnar epithelial cells + basal cells.
Outside the epithelium is connective tissue and smooth muscle.

Secrete PSA but usually doesn’t reach blood. Liver PSA reaches blood. But in prostate cancer, prostate’s PSA can reach blood.

Note that all accessory glands are dependent on dihydrotestosterone, more potent androgen than testosterone.

Hypophysectomy picture darker than castration picture.

Question 30

Fluid absorption

Answer 30

If the vasa efferentia are ligated fluid will accumulate, fluid leaks into interstitial space, germinal epithelium damaged, and spermatogenesis ceases.
If vas deferens ligated, nothing happens.

Vasa efferentia ligation picture: lumen looks very big.

Question 31

Velamentous cord insertion

Answer 31

Umbilical cord insert into foetal membranes instead of the chorionic plate. This causes vasa praevia, and the vessels are prone to rupture causing ante-partum haemorrhage, especially if vessels are near the cervix, as they’re not protected by Wharton’s jelly.

Normally, the blastocyst implants with the inner cell
mass orientated towards the endometrium. If the blastocyst implants on its side, then the connecting stalk has to grow down over foetal membranes to reach the placenta.

Question 32

Chorion frondosum and chorion laeve

Answer 32

Initially villi are formed over the entire chorionic sac, giving rise to the chorion frondosum.
By 20 weeks, villi have regressed from the superficial pole, leaving the chorion laeve. It is this part of the chorionic sac that ruptures during delivery,
and through which the baby is born.
Villi persist only over the deep pole of the chorionic sac.
Regression of the villi gives the placenta its discoid shape.

If regression is incomplete, remnants may persist as accessory or succenturiate lobes.

Question 33

Multiple pregnancies

Answer 33

In dizygotic twins there are always two chorionic sacs.
In monozygotic twins, number of chorionic sacs depend on when splitting occurs, and hence whether one or two blastocysts are formed.
Vascular anastomoses frequently occur in monochorionic placentas (share one chorionic sac), and imbalance in blood flow can result in the twin-transfusion syndrome. One twin (the recipient) becomes
dominant and receives blood from the other (donor twin).

Question 34

Oviduct

Answer 34

Epithelium, smooth muscle, serosa. Near the ovary, lumen looks very disjointed. Near the uterus, lumen look more organised.
Epithelium contains pale ciliated cells and dark NON-ciliated cells.

Question 35

Vagina

Answer 35

Pro-oestrous: Oestrogen causes keratin production within the squamous stratified epithelium.

Oestrous, during ovulation: Keratin layer is at the surface of the vagina. Protects from mechanical damage.

Dioestrous: Progesterone causes neutrophil recruitment.

Pregnancy: Now progesterone causes production of goblet cells.

Question 36

Uterus

Answer 36

Oestrogen promotes development of simple tubular glands in endometrium. The glands contain SIMPLE epithelium.

Progesterone: Myometrium, epithelial cells of endometrium proliferates, glands become more branched.

Question 37

Pseudopregnancy

Answer 37

Mating an oestrous rabbit with a vasectomised male or stimulation of the vagina during oestrous
produces a similar sequence of ovulation and subsequent corpus luteum formation inducing
pseudopregnancy

Serosa, longitudinal, circular smooth muscle, endometrium.

Question 38

Type of secretion

Answer 38

Apocrine = holocrine: type of secretion where a part of the cytoplasm is lost with the secretion. Apocrine for lipid secretion.
Merocrine = eccrine =exocytosis: type of secretion where a membrane bounded secretory
product is released by fusion of that membrane with the plasma membrane. Merocrine for protein secretion.

Question 39

Placenta

Answer 39

Arteries run superficial to the veins over the
chorionic plate. The umbilical cord is usually attached close to the centre of the chorionic plate.

Placenta abruption: Placenta separates from the uterine wall prematurely. Placenta appears pale. Cause IUGR.