UTERINE INVOLUTION IN CATTLE

Rahul KatiyarPhD Scholar

Div. Of Animal Reproduction Roll No.- P-1856

Introduction• Puerperium period is the period after the completion of

parturition, including third stage of labour when the genital system is returning to its normal non pregnant stage.

• Extension of puerperium may have detrimental effect on reproductive performance of animal.

Normal Postpartum Reproductive Endocrinology

• The altered ratio of progesterone: estrogen in favor of later, up regulates the synthesis of uterine prostaglandins (PG) and labour

(Liggins, 1973; Thorburn, 1991; Challis et al., 2000)• The PGF2α levels parallel the rate of uterine involution with a

peak at day 4 postpartum and thereafter remain elevated for up to 20 days.

( Kindhal et al., 1980; Lindel et al., 1982)• Progesterone levels decline rapidly during the last 48 hours

before parturition and remain at very low levels(< 0.5 ng/ mL) throughout the early postpartum period.

( Kesler et al., 1977)

4 main areas of activity

Shrinkage of tubular genital

tract

Restoration of endometrium

Resumption of normal ovarian

function

Elimination of bacterial

contamination

Involution

• Reduction in size of genital tract is called involution.• Occurs in a decreasing logarithmic scale.

• Reduction is size of myofibrils from 400-750 µm on first day to less than 200 µm over the next few days.

• Diameter of the previously gravid horn halved by 5th days and its length halved by 15 days. ( Gier and Marion, 1968)

• Uterus is palpated per rectum by 8 and 10 days postpartum in primiparae and pluriparae respectively.

• Biometry of gravid uterine horn-

( Morrow et al., 1986)

Days Pospartum Diameter of gravid uterine horn

Between 4-9 days 12-14 cmBy Day 14 7 cmBy day 25 2-4 cm

Myometrial contractions are responsible for reduction in uterine biometry

• Reduction in uterine size and volume is brought about by myometrial contractions.

Myometrial contractions

Reduction in over all size

of uterus

Discharge of debris

Dischrge of fluid

Compression of uterine

vasculature

Changes in cervix• Cervix undergoes atrophy and shrinkage due to elimination of

fluid and reduction in collagen and smooth muscles.• Involution slower than Uterus• Complete involution by day 30

Mean external diameter ( cm) Days postpartum15 2

9-11 10

6-8 30

5-6 60

Restoration of endometrium• During the first 7-10 days after calving there is noticeable loss

of fluid and tissue debris which is referred as ‘secondary cleansing’ or ‘secundus’.

• Volumes varies greatly from individual to individual.• Greatest flow of lochia occurs during the first 2-3 days.

Endometrial repair• Necrosis of caruncular tissues

• Sloughing of the caruncular tissues

• Reorganization of uterine endometrium

Early necrotic changes in septal mass of caruncle

Constriction of caruncular blood vessels

Sloughing of necrotic material day 5 PP

Small blood vessels protrudes from surface of caruncles

Sloughing is complete by day 15 PP

• A systemic response is also observed due to tissue damage and inflammation.

• Acute phase protein increase rapidly after calving, reaching peak at 1-3 days before declining to basal levels by 2-4 week. ( Alsemgeest et al., 1993; Sheldon et al., 2001)

• Acute phase proteins limit tissue damage and promote tissue repair. (Baumann and Gauldie, 1994)

Return of ovarian activity (Ovarian rebound)

• The pitutary is refractory post-partum, immediately post-calving to GnRH (Lamming et al., 1979).

• Emergence of first follicular wave between days 7-14 post-partum.

• The first follicular wave can be detected with the first dominant follicle ≥ 9 mm in diameter being identified at around 10 days (Savio et. al., 1990).

• One follicle develops increased number of LH receptors and IGF-1 binding proteases ( Roche, 2006).

• Dominant follicle ovulates in 30-80 % of cows, becomes atretic in 15-60% of cows; becomes cystic in 1-5% of cows. ( Roche, 2006).

• First ovulation occurs at on average at 21 days in dairy cattle. ( Adams, 1999).

• Many of the ovulations of first dominant follicles are not associated with behavioural signs of estrus. (Moller, 1970; King et al., 1976; Kyle at al., 1992)

Elimination of bacterial contamination

• Very high bacterial contamination rate during first 20-30 days post-partum, with a subsequent decline, so that, in normal healthy cows, the uterus should be sterile by 6-8 weeks post-partum. (Sheldon at al., 2002).

• Main mechanism involved is by phagocytosis by migrating leucocytes.

• Phagocytes also release TNF-α and interleukins.(Shelson, 2004).

Thank You