\1. !■ A rilOLOGY 013 



in I'iit.s sul'tciiiifi; troin tcnniiinl slajics of hiotiii (Icficicticy tiic coinplcinoiit 

 titer of tlic plasma n\i\y lu' (•onsidcral)!^' I'cduccd. IJats tod Ihc l)i(»t iii-dcfi- 

 ciciit (lid t)iil iii\('ii a(l(M|ualc liitiliii daily iVoiii llic lime of weaning liad 

 iiil't'ftioiis with T. I(ii-/s/ that were no dilTcrciit Ironi the iiitcctioiis in rats 

 fed a normal stock diet. Mxccss biotin administcfcd to nofmal fats had no 

 proto('ti\'i' Of cufalixc ('flVctson infections with V. {civi.si or T. cqidpcnluni.''^ 



XI. Pathology 



PAIL CiVOlKlV 



The \Msiblo, gross pathological changes in liiotin deficiency in various 

 animals and man luive been described as scaly, sel)orrheic dermatoses, 

 often accompanied by alopecia. 



The microscopic picture was best studied in rats.'"^ The skin shows ex- 

 tensive hyperkeratosis, some parakeratosis, acanthosis, and edema. Broken 

 hair shafts and serous crusts are intermingled with the hyperakeratotic 

 lamellae. There is dilatation of the follicular shafts, and the glandular 

 orifices are often plugged with hyperkeratotic material. Surprisingly little 

 cellular infiltration accompanies the marked changes in the epidermis and 

 the edema in the corium. The connective tissue is slightly edematous and 

 dissociated. Most striking is the presence of numerous dilated and hyper- 

 emic blood vessels throughout the corium. There is no evidence of endo- 

 vasculitis and no perivascular infiltration. In the late stage of the disease 

 there is some atrophy of the epidermis, which contrasts with the abundant 

 hyperkeratosis. There is an e.xcessive amount of sudanophilic fat in the 

 hyperkeratotic lamellae; as the skin lesions vmdergo imolution the normal 

 epithelium is restored with slight damage to the fibrous connectixc tissue 

 but with no distiu'bance of the (^lastic fibers. 



In contrast to the picture seen in rats, kcn'atosis is only moderate in the 

 mouse suffering from biotin deficiency. The pil()sel)aceous orifices ai'e di- 

 lated in deficient rats but only rarc^ly in the mous(\ The stratimi corneum 

 is sudanophilic in deficient I'ats, but it is only mil(ll\' so in the mouse. The 

 subcutaneous fat depots are resorbed in deficient rats, but they remain 

 virtually unchanged in the mouse. In tlu^ sel)ace()us cells, the stored lipid 

 droplets are much laigcr I lian in t hose of normal animals. There is abundant 



' M. Sullivim .-iikI .1. .\icholls, Arch. Dermatol, and Si/philol 45, 295 (1942). 



2 C. M. Findlay and U. (). .Stern, Arch. Jyiacase Childhood 4, 1 (1929). 



3 P. Gyorgy, M. Sullivan, and H. T. Karsncr, rmc. Soc. Exptl. Biol. Mr. I. 37, 313 

 (1937). 



^M. Sullivan, L. Koll), ;iihI J. Xiclioll.s, Hull. Johns Hopkins Hosp. 70. 177 (1942). 



