Riesgo, Planes y legislación

gives the following deSCription o� th

e

tunicn dartos.

The

tuniCfl dartos i 13

a

smooth i1I18cular coet oonslsting ot two

layers. The outer layer 1s vera-

de

licate, clings cl08el7

to the akin of the

scrotum and

has t1bres arranged 1n various

d1rections.

'l'he inner and b7

f'or

the stronger lqer consists of nusculnr fibres which

f'or

the greater port

are

turned 1n

the dirac

tion f'rom

the onus to the root of' the penis.

In

the reg ion of

the raphe the tuniCfl dartos turns over on th

e

connecti va tissu

e-

like

d1 Y1d1ng

wall

ot

the sorotwn; thus efich testis reste i

n an lndl T1dual

sao

ot

eroooth nJ18oulatUl'e.

( 184)

PhIllips et

al

studied the phJsiologv ot the tunica. dal'toe ot th

e

ram and stated thnt i t

�

ctions

ver'3

much

_fiS n thermos1;s t would. turn1sh1ng the mecho.n1am by whioh

tho therrrr>-regula1;ory tunct10n

ot

the scrotum 1s flccOl1i>llshed. �warrnth causee a relaxatIon ot the dartos l1I1scle with a

conse,�uent removal

of

the

te

st_es _:trom the warmer �

te

l'Ji)

e

re

tures

whereaf) J.owering of

extemal. teqJorature results in

1ts

oontrc ctlon,

hoJ.d1ne

the testes

close

to the bo�

( 184) ( 180 )

•

At intermediate

ten(>el"fltUl'cs there i s oonstant adj ustment , the dartos contracting end relax1ng 8S a result

of' very

emel.l

<'1eorenaes

or increases in sorotal temperature.

( 184)

In rame , Phillip s ot al round t

ha

t even the isolated

dortoe

reacted �u1okly to temperature changes, contr�ct1ng us the temperature decreased and

relaxing

as it inorease�

They found 1t to be moat sensitive to changes at temperatures approaohing the normal scrotal temperature.

( 197 )

In

his work with humnna and doge Lieben round the dartos to reaot

even

when fa

r

_{removed spots 1n}

the bo�

were

st.1mulated b� applioatlons ot _{warm or c}

o

ld water or

- 115 -

by

t

he sympathetic and para$YmPathetlc nerYous �stem 1n

such a manner that each scrotal halt recei

v

es

1

tB nenee tram

the abdom1nal cord on the serne side. Irritation of the

sympathetics and the ramus communions tram the tirst two sacral segments resul

t

ed in contraction ot the _dar\08 but

there were no contractions when nerves from other segments

( 197 )

were irn tated • It appears tram this observat ion that the

c

ontraction or relasotion ot

t

he dartos, as the caso may be. is etrected through the reaction ot these nerve&

( HI8 )

Tho eJ�per�nt8 carried out by Phillips

and

_An4revs

indicate thut 1n the ram the tunica danae

is

dependent upon

Q testi cular hOl'm)ne for the development and maintenance ot

ita rU6ct1vity to

temper_ature ohanges.

From all this evidence 1t appears certain thnt the ecrotwn is an organ the rtmction ot wbloh is to regulate the t emperature of the testee

and

that such regulation Is

e ssential tor maintenance at oonttaaed germ cell d1tterentlatSan

in monrnals including the tarm animals.

Tho fertUi ty of a dairy bull or a 4al17 cow is roore o r l e s a interdependent.

The

fen1l

1

ty or the

rep roduct

1

ve efficiency 1s ord1ntll'Uy judged by the nWDber

at 1nsem1ntlt10na re�uired pe_r conception but thi s number depentJs as much on the �roductivc efficiency at the cow as that of the bull.

The effect of temperature on tenili

t

y has been

conclusivelY shovln In

la

borator,y on1male.

( 52 )

M11l s carried out an e�er1ment with whUe mice under controlled condi tiona. Keep1ng other �actors e. g.

nutr1tion, 11ght etc. un

1

form and var¥1ng the temperature o

1t

was

found

that, at the " stimulating ooolness"

(60-'10 1') ,

the mice were

born in

large l

1

tters o� "highly viable �oung, "

- 116 -

g�ew most vapidly ur4d matured ear1 1eo� Se�

cycle Btnr�ed

eurly. Immed1ste concept1on

toll

owed

almost eve%7 adult

nw. t1ng D.lld the �oung born were of greu tor lnd1

vidual s

i

ze.

t;''ll.on the mice were aubj octad to condi tiona of high teov?erature

o

( 5 9 -

�2 F')

&nd bWil1d1t¥ 1 60

-

'10'';) groTrth

wae greatl1'

retardo(1

and mnWri� Ilmch dela.Yed und this

differenoe

in development wns maintained throughout the lite span. � alJPtlrent� heal

t�

ramaleo raisod _1n this lOOiu_{t heat} never

concoived, although

rooted ro� eute� with ou·tslde normal

males of known hlgh fortU1ty. Doth melee and

temales

mated jUDt as freely and with £i.a much zest at) did those

in

the

cold

rooms.. It Wf48 concluded that the

lack

01'

reproductivi ty

of the hot

roon _m10e .las due 1.0 actual supp res si on or gonadal tissue activ1ty _{in the}

sex gland�

The .author further stated _{that " there seems to be} an

apt1.a.uu env1ronmental teDi)crature _{for ·�he lOOuse,} pl'Obab17 o

around 7C F. , with de,prsssion of growth rate and �er\llit�

o

0

i f' t emperatura rall� belo�1 65 .F

or

ri ses rar above

70

F. "

The evidenceD so tar obtained

w1th

da1�

oattle

have not been DO c10ar

cut as

in the

case

o-r laboratory

nn1mels such

an mice etc. The main reesona tor thi s are : - ( l ) these lClrge animal S Cf.JUlot 'b e so eas1ly handled,

( 2 )

the C

Xp

er1ment i s t1rue-consuming and t7nJ'e expens1

yet

( 3 )

c.

sufficiently

b1g space

1s

roq,uired

to handle a :tair�

large number of

un1mala: (4)

the

c

on

t

rol.l.

1ng

o-r

all

nccesso.r:,· conditions

in

a bigger spac e w1th larger an1mala 1s difficult. In

v1ew

of tbeso dlff1cult1es no e�er1ment hus been made an 'the offect ot

tomperature

on the

r�voduc tive cupacit�

o�

da1.� cuttlo under controlled Var10us

general

observations

mude

b� d1�:f"erent _workers in �f'erent countries, however, indicate the

effeot

of' tomparstUl'9 f'a1rly oonclusively.

- 117 -

on

'rho

quality

of the

semen o-t a t_e

r

tile bull is j udg0C1 from the

following prope�1ee � -

Volume

ot

the

In document RIESGOMAP (página 58-61)