A NOTI~ ON PITUITAP~Y DWAPdrI81\I IN TIII~ NOUSI~

B~: C4.. R. Ds BEER A~D HANS GPoI'TNEBERG

(With Two Text-figures)

Ws had intended to study the developmen~ of the pituitary gland in mice homozygot~s for the recessive gene for pituitary dwarfism (Snell, 1929; Smith & NacDowdl, 1930, I931), The aim of this investigation was

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Fig. 1, A. Average g r o ~ h curve of nine normMs {solid line) and individual growth curve of one dwarf (broken lh~e). B. Average growth era're of six normals (t, hick solid lh~e) a.nd in&ividuM growth curves of two dwarfs (thin solid line and thin broken line).

CO trace the condition back to its very beginning in order to find out whether eosinophil cells never make their appearance in the anterior lobe of ~he gland, or whether they disa.ppear secondarily. As the work li~s now been interrupted, we thigh it advisable to publish the few data in our possession in ~he hope that they may ]De of some use for o~her inves~iga%rs.

@rowth m~rves (weighings at 2¢ hr. intervals) of two liCters cont, Mning Jwarfs are given in Fig. 1. The birth weig]~ts of normals and dwarfs

2,98 A Note on P i t u i t a r y D,warfis~Jt ~'~ tTze M o u s e

overlap considerably. Our data are insnl~cient to decide the quesdo.n whether there is-a statistical diF:ereace between the birth weights. The growth curves show that the dw~arfs tend to gro~ at a reduced rate already during the first !!ew &~ys of life. @rowdz stops altogetl~er at or shortly before weaning age.

The reduced growth rate of dwsrfs in theb ear].y post-natal life makes it possible to diagnose dwarfs wide a fair accuracy ~t an earlier date tha~a has hitherto bee n possible. The criterion for $he diagnosis is not only the absolute weight at the time of ~t~e examination, but also the ratio of final weight/birth weight, A litter containing eight surviving young had the following ratios of final ~mighi/birth weight at the ages of 6 and 7 days :

f'i*~o.a ~v@tzt/birth "z.ve{ql~t

d~ys t 2 3 4~ .5 6 7 8 6 2+07 2.10 2.0:5 2.04 1..97 2-02 1+82 1.17 7 2,43 2.40 2-38 2,35 2.33 2-14¢ 2~01 1.32

Considering the ratios at the age of 7 days, i9 is fairly dear %bt% pre- sum.ably %he §.rst five animals ~re nor~als end that the last one is pres,~mably an (unustlally poor) dwarf. Animals 6 and 7 are more doubtful. }Iowever, animeJ 6 was still well within d~e normal range on th.e sixth day, and it was probab]y aoddental that it gained eomparative]y [ittle during the seventh day of life. This renders i.t ~ikety that the border- line between normals and dwarfs is to be drawn between animals @ and 7.

This tentative classification me.de olz the basis of the growth rat~s was confirmed histo].ogicatly. The animals were killed on the seventh day and their pituitaries fixed m Zen.ker formol. Sections were cut 2b~ thick and sta~ined in a;id fuchsin followed by aniline blue and orange G, or in Nallory's phosphotangstis lmematoxylin with arld widmub previous treatment wbh Keidenhain's lm, ematoxylin. By ~he former method the eosi~mphil cells appear brigh~ red; by the tatf, er, a :rich mauve.

The res~t[ts obtained by all these methods were consistent. The, pituitaries of two animals, nos. 7 and 8, showed no eosinophil ceils in the a~).tedor lobe. In all the remai~nder, eosinophil cells were presen< tho~tgh ia differing qlm~dties. They were most m.~merou.s in animals 2 and 5, while in I, 3, ~ and 6, the eosinophil cells were present in lesser, but approximately equal qu.aatides.

~ig. 2 gives a{ the same magni~e.atio.o the eo~.eeatratimzs of eosinoj?hil cells in typical fields of ¢,he anterior lobe of all eight animals.

G. 1%. r)~ 7BE~.~ .,~>,~o HAm, s G>O>v:~Bv,:aa 299

The histological investigation thus fully confirms the classification made on the basis of the g~.owtk rates. Ah:eady a.t the age of 7 days, tha%

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[Pig. 2. ~xpl~na{,ion in ~he text.

is to Seoy, 20-.1,i days before the eessa,tion of growth, no eosinophil celIs are found in ~he anterior lobe o5 the pituitary gland of the presumed dwar£s. Amongst ~he z~orm~]s, some differences occur as ~o the abun-

300 A Note on Pit'~dta'ry Dwarfism in l:he Mouse

dance of eosinophiI ceils. ~t is conceivable ~hat su@ diffe~:ences distin- guish heterozygo~es fz'om homozygous normal animals. In view of ~he small uamber of anim~ds investigated and iu the abseuce of ~ y direct proof, this is no more [hma a suggested possibility which should be rein~'estiga~ed.

BEFER.~NOES

S~w~, P. E. & 5'L¢cDow~Lr~, E. C. (1930). A'~c~t. ~ec. 46, 2~9. - - - (t931). Anat. P, ec. 50, 85.

S ~ L b , G. D, (1929). Proc. ~at. Acct~t. Sc, i., [Vc~sh., 15, 7:~3.