Cytological studies of bovine half-embryos

THERIOGENOLOGY

I CAL

CYTOLOG L. Centre

de

12.6

after oestrus and --in vivo

half-embryos buffered

(FCS),

or the

the

some

end

tively.

h

culture

halves Considering

including l-4

“Good”

as

were

halves

heifers

l-4

h

J

for

73%

at

It

culture

at

3JoC

in

classified

culture) being

phos-

at

from designated

present 6-10

the

grade

A

purposes. h

(IS)

6-10 T’Ile

culture and remaining

h (37)) results

or

18-24

h

58% were

3 on unpaired viable were

at 12 h apparently

(53))

SEM) cells of 23.Ok2.1

of

82% 50%

not

morphologically fixed for cytological

of 45.9A3.4 (& had an average ten

in vivo, ly, Tpnterally

O=day

The

of

halves); 60% (Colcemid (46). but was omitted

into

“good” analysis.

which cells

33% and

24 h culture, without agar, concluded (2)

from

the

differ

JO% of

of

the

could

4 h added

half-embryos

the corpus wet-ml

periods while

after was

were frozen Ann. Med. 1982. in agar cylinders

of

to Nine

which

(29)

’

pairs

estrus).

percentages

(12

24 h group

is

(day

fixed.

Renard al _et -* were embedded

ture;

their viaand freezing

61% and 15% of the pairs, respecfrom these pairs individually,

after various the half-embryos, fixed for chromosome analysis

Half-embryos

After those

were

pairs),

during their of half-embryos

had an average “Poor” halves

Day

or

5% after in each

pairs

They

(46

superovulated

evaluate sexing

20% fetal calf serum medium (MEM)+20% FCS or

sometimes during A and B embryos

viable in 6J%, each half-embryo

their viability transcervical

at

Day 75. To sex half was 2 h

Vete-

Quebec,

pyknotic.

To assess transferred

frozen

Medecine

from

to of

monozygotic

“non-viable”

for

observations),

pyknotic.

collected

cells.

(and

65 observations the percentages

(94

57% were

de

Saint-Hyacinthe,

supplemented with minimum essential

at 18 h (34) and 42% at 24 h (72). influenced by the type of medium used. Each of 35 divided embryos was separated and “poor” halves after 24 h culture and were

Faculte

5000,

embryos

endometrial period

of

ha1 f-embryos, at

BETTERIDGE

were bisected the possibility

cultured

to D (degenerated), and C and D embryos

both

and

bovine

(PBS) in cases,

culture

lent)

(47),

were

FCS+bovine

of

(excel “viable”

days and

saline

in

MEM+20%

HALF-EMBRYOS

K.J.

Animale, C.P.

6 or J in vitro _-

phate

At

Montreal,

micromanipulation,

them. The

end

Reproduction

de

ANu

JC6.

JZS

heifers bility

OF BOVINE

KING

en

Universite

Canada, By

PICARD,

Recherche

rinaire,

STUDIES W.A.

be

culture

the

the

“good”

half

sexed

were:

5% after

(20); for

last

were to

luteum, pregnant

10

10 at

“poor”

was

either

17% after h

(20)

4 h of

and

culture

2 h group).

and thawed in French straws vet. 126:23-32). Of these, __ (Willadsen, 1979. Nature

half-embryos

frozen

within

(after 14 halves

2JJ:298-300).

agar,xd

6% of

developed. that

half-embryos:

morphologically

(1) according

tend to

to

degenerate

their

complement

in

culof

via-

ble cells; (3) give a high pregnancy rate after twin transfer; (4) can be sexed satisfactorily by chromosome analysis using 4 h culture in and (5) can be frozen more efficiently if protected in agar. colcemid, in combination, the techniques provide a means of storing viable, Thus, (Supported by grants from CRSAQ sexed half-embryos for other studies. and

252

CRSNG).

JANUARY

1984 VOL. 21 NO. 1