(a) Describe the prostate under the following headings:
(i) Gross features
(ii) Lobes
(iii) Capsules and ligaments
(iv) Blood supply
(v) Lymphatic drainage
(vi) Age changes
15 marks
(b) Describe the key events occurring in the ovarian cycle with refe

Question

(a) Describe the prostate under the following headings:
(i) Gross features
(ii) Lobes
(iii) Capsules and ligaments
(iv) Blood supply
(v) Lymphatic drainage
(vi) Age changes
15 marks
(b) Describe the key events occurring in the ovarian cycle with reference to their hormonal basis. Enumerate the diagnostic tests for ovulation.
15 marks
(c) (i) Discuss the principle and steps involved in Polymerase Chain Reaction (PCR). Mention any five of its applications in clinical medicine.
10 marks
(ii) Write a note on different vitamers of vitamin B₆ and write their biochemical role in cellular metabolism.
10 marks

UPSC Answer Check · Accepted Answer

Prostate. The prostate is a walnut-sized, 20–30 g gland below the bladder, anterior to the rectum, through which the prostatic urethra passes. Grossly it has a base at the bladder neck, an apex at the urogenital diaphragm, an anterior surface, a posterior surface with a median sulcus, and lateral surfaces; the seminal vesicles lie posterolaterally. The posterior surface is related to the rectal ampulla and is palpable on digital rectal examination. Historically it is divided into five lobes: anterior, posterior, middle, right lateral and left lateral; the middle lobe surrounds the prostatic urethra between the ejaculatory ducts and is the common site of benign prostatic hyperplasia causing bladder outlet obstruction. Clinically, zones are more useful: peripheral, central, transitional and anterior fibromuscular stroma. The true capsule is the inner fibromuscular capsule; the false capsule is the outer periprostatic/endopelvic fascia. It is supported by puboprostatic ligaments to the pubic symphysis and vesicoprostatic ligaments to the bladder neck. Blood supply is mainly from the inferior vesical artery, with contributions from middle rectal and internal pudendal arteries; venous drainage is through the prostatic venous plexus of Santorini to internal iliac veins. Lymphatics drain to internal iliac, external iliac, sacral and obturator nodes, with upper prostatic lymphatics to external iliac and lower to internal iliac. Age changes include pubertal growth under androgens, benign prostatic hyperplasia after 50 years, carcinoma commonly in the peripheral zone, and prostatic calculi.

Ovarian cycle. The ovarian cycle is the 28-day sequence of follicular development, ovulation and luteal formation, controlled by hypothalamic GnRH and pituitary gonadotropins. In the follicular phase, pituitary FSH dominance stimulates granulosa cells to aromatise theca-cell androgens into estradiol; rising estradiol first gives negative feedback and later, with a dominant follicle, positive feedback. The preovulatory LH surge, triggered by sustained high estradiol and permissive progesterone, causes follicle rupture and ovulation. Ovulation is usually around day 14 in a 28-day cycle. In the luteal phase, the corpus luteum secretes progesterone dominance with estradiol, preparing the endometrium; if fertilisation does not occur, it regresses, while hCG maintains it in pregnancy. Diagnostic tests for ovulation include basal body temperature showing a postovulatory rise, urinary LH kit detecting the LH surge, ultrasound follicular tracking, serum progesterone on day 21, and endometrial biopsy showing secretory changes.

PCR. Polymerase chain reaction amplifies a defined DNA segment using two primers, dNTPs, Mg2+ and a thermostable DNA polymerase in a thermal cycler. The steps are denaturation at 94–95°C to separate strands, annealing at 50–65°C for primer binding, and extension at 72°C with Taq polymerase; repeated cycles yield exponential product, detectable by gel electrophoresis or fluorescence. Specificity depends on primer design and annealing temperature. Clinical applications include HIV viral load monitoring, tuberculosis diagnosis, COVID-19 RT-PCR, genetic screening and forensic DNA profiling.

Vitamin B6. Vitamin B6 exists as pyridoxine, pyridoxal and pyridoxamine, and their phosphorylated forms pyridoxine-5'-phosphate, pyridoxal-5'-phosphate and pyridoxamine-5'-phosphate; pyridoxal-5'-phosphate (PLP) is the active coenzyme. PLP forms a Schiff base with enzyme lysine and participates in cellular metabolism through amino acid transamination, decarboxylation, racemisation and transsulfuration. It is required for glycogenolysis as a cofactor of glycogen phosphorylase, for heme synthesis by ALA synthase, for niacin synthesis from tryptophan, for neurotransmitter synthesis such as dopamine, serotonin, GABA and histamine, and for sphingolipid metabolism through serine palmitoyltransferase.

Thus, the prostate is described by its gross anatomy, lobes, capsules, vascular and lymphatic drainage, and age-related changes; the ovarian cycle is governed by FSH, estradiol, LH and progesterone; PCR is a stepwise amplification technique with major clinical uses; and vitamin B6 vitamers function chiefly through PLP in amino acid, glycogen, heme, niacin, neurotransmitter and sphingolipid metabolism.

(a) Describe the prostate under the following headings: (i) Gross features (ii) Lobes (iii) Capsules and ligaments (iv) Blood…

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