Histo Final 2023

Question 1

List at least three histological differences between blood and lymphatic vessels.

Answer 1

Blood vessels -
>Artery,, Tunica intima- elastic fibres gives it a rough surface, endothelium
>Thick tunica media and thin tunica adventitia with regards to vein.
>Blood flows under high pressure in arteries so lumen is very think
>Vein,, Tunica intima- no elastic fibres giving it a smooth surface
>Thin tunica media and thicker tunica adventitia with vasa vasorum. Valves present
> Lumen not as think as low pressure in vein (valves prevent backflow of blood

Lymphatic vessels -
Lymph capillaries- enter lymphatic collecting vessels, similar to blood vessels (3 layers) but thin and delicate
Have one way minivalves allowing excess fluid to enter but not leave, very low pressure. Picks up bacteria and viruses along with proteins, electrolytes and fluid (lymph nodes destroy most pathogens)

Question 2

Characterise the histological structures of the outer layer of the heart.

Question 3

What is the choroid plexus - Characterise this histological structure, its location and function

Question 4

List all cells of the white pulp parenchyma and briefly describe the roles of each of them

Question 5

Which part of a lymph node is thymus-dependent and which thymus- independent and what does it mean?

Answer 5

The paracortex is the thymus-dependent zone while the Cortex is the thymus independent zone. Lymphocytes B are found in the cortex and may or may not need the Lymphocytes T that are found in the paracortex to activate.

Question 6

Name and describe the histological structure of the zone responsible for adrenaline production

Answer 6

Epinephrine chromaffin cells in the medulla of the adrenal gland
Medulla
Derived from neuroectoderm
Contains Endocrine cells and Blood vessels
Endocrine cells are irregularly arranged short cords surrounded by capillary networks
Numerous granules that stain by chrom salts = Chromaffin cells

Question 7

Characterise all histological structures of the glandular part of hypophysis

Answer 7

Posterior pituitary = Neurohypophysis - pars nervosa, infundibular stalk. Median eminence, Unmyelinated nerve fibres - Herring bodies, Neuroglial cells: Pituicytes, Fenestrated blood vessels.
Hormones -> ADH and Oxytocin

Anterior pituitary = Adenohypophysis - pars distalis, pars intermedia, pars tuberalis
Endocrine cells, blood vessels, stroma with LCT, Acidophils and Basophils
Hormones -> Growth hormone, FSH, TSH, Prolactin, LH

Question 8

Give one example of each type of tissue present in the tongue

Question 9

Give 2 morphological differences between pneumocytes I and II

Answer 9

Pneumocytes I are squamous cells responsible for gas exchange, they form an air-blood barrier where gas exchange occurs.
Pneumocytes II are cuboidal cells in the microvilli, they release surfacant.

Question 10

Name the type of epithelium that lines the trachea

Answer 10

Pseudostratified epithelium

Question 11

Characterise the histological structures of the duodenum villi

Answer 11

Plicae, Microvilli, Crypts of Lieberkuhn

Question 12

List and briefly characterise the function of CNS and PNS

Answer 12

CNS - Astrocytes (fibrous and protoplasmic)
- Oligodendrocytes
- Microglia
- Ependyma
In the CNS, glial cells regulate neurotransmission and help for the blood-brain barrier. They also clean up dead neurons, synchronise nerve impulses, and regulate brain metabolism

PNS - schwann cells
- satellite cells
In the PNS, Schwann cells create a myelin sheath for faster conduction of nerve impulses and satellite cells assist in regulating the external chemical environment.

Question 13

List in proper order all parts of the nephron and characterise the main functions of each of them

Answer 13

Glomerulus- filters blood
Bowman’s Capsule- filtration of blood from the glomerular capillaries
Proximal convoluted tubule-reabsorbs most of the glucose, amino acids, and small peptides that enter the ultrafiltrate
Thick descending limb of loop of Henle-reabsorb water and sodium chloride from the filtrate
Thin descending limb of loop of Henle- II II
Thick ascending limb of loop of Henle- II II
Thin ascending limb of loop of Henle- II II
Distal convoluted tubule- reabsorbs Na+ from filtrate and transports into interstitium. Transfers K+, NH4+ and H+ into filtrate from renal interstitium.

Question 14

Describe the histological differences between the proximal and distal parts of the epididymis

Answer 14

Proximal- 1 single layer of smooth muscle, two rowed tall pseudostratified columnar epithelium, very long microvilli (stereocillia) on the surface of epididymal epithelium
Distal- 3 layers of smooth muscle, shorter two rowed pseudostratified columnar epithelium
Function - Accumulation, storage and maturation of spermatozoa

Question 15

Draw a mature follicle and mark all details (graafian follicle)

Answer 15

Theca externa
Theca interna
Antrum
Granulosa cells
Corona radiata
Culumlus oophorus

Question 16

List all phases of prenatal embryo development

Answer 16

Germinal, embryonic, foetal phases

Question 17

List all steps of fertilisation

Answer 17

Capacitation, Acrosome reaction, Adhesion of sperm, Penetration of zona pellucida, Fusion of cell membranes, End of second maturation division, Formation of pronuclei, Karyogamy

Question 18

What is CRL

Answer 18

The measurement of the length of embryo and foetus from the top of the head (Crown) to the bottom of the buttocks (Rump).

Question 19

Describe how twins with common amnion and chorion develop

Answer 19

Monochorionic and monoamniotic twins or mono-mono twins develop when an embryo doesn’t split until after the single amniotic sac is formed.

Question 20

Characterise the placenta of a dog based on the following
a. The structure of the chorion surface
b. The placental barrier -
c. The degree of invasion -

Answer 20

a. The structure of the chorion surface - Zonary placenta. The chorion frondosum is organised into a broad belt extending around the longitudinal axis of the embryo where it forms lamellae, so it is known as zonary and lamellar. The lamella may be more or less branched and twisted resulting in the formation of the labyrinth

b. The placental barrier - Maternal endothelium vessels, fetal epitelium vessels= trophoblast, fetal connective tissue, fetal endothelium vessels.

c. The degree of invasion - Deciduate (invasive) - The intimate connection between fetal tissue and uterine - conjoined placentation.

Question 21

What is the essential difference between invasive and non-invasive placenta?

Answer 21

Adeciduate-non invasive- there is no fusion of the maternal and fetal tissue, and separation is easily achieved at parturition without damage to maternal tissue. In Horses, pigs and ruminants. Eg. diffuse and cotyledonary placentae.
Deciduate-invasive : The intimate connection between foetal tissue and uterine. Some maternal tissue is lost with the foetal tissue at birth. In carnivores, humans and rodents e.g. zonary and diffuse placentae.